1. Field of the Invention
The present invention relates generally to a homezone service method in a mobile communication system, and in particular, to a method for providing a call forwarding service on a PSTN (Public Switched Telephone Network) number as well as an MDN (Mobile Directory Number) number in a homezone.
2. Description of the Related Art
For a homezone service, a service provider allocates a specific zone, called a “homezone”, to a mobile phone subscriber, and then applies different call rates to a call made in the homezone and a call made in a non-homezone.
For example, if a mobile subscriber has applied for the homezone service by designating his home as a homezone, the service provider will charge the subscriber a call rate equal to a wire call rate for the call made in the subscriber's home (i.e., homezone) using the mobile phone, but will charge the subscriber a normal call rate of the mobile phone for the call made out of the subscriber's home (i.e., non-homezone). To this end, the mobile phone is assigned two numbers: one is an NSN (National Significant Number) number based on the PSTN number system used for charging the call made in the homezone and another is an MDN number used for charging the call made in the non-homezone.
It is conventionally available to provide a call forwarding service on the MDN number. The conventional call forwarding service, however, is based on a common mobile communication system that does not provide the homezone service. Therefore, a call forwarding service on the NSN number allocated for the homezone service has not been fully considered heretofore.
FIG. 1 shows a conventional method for providing a call forwarding service on the MDN number. An originating MSC (Mobile Switching Center) provides a service to an originating subscriber. For a call originating using the PSTN or other networks, the originating MSC becomes a gateway MSC. A terminating (or serving) MSC provides a service to a terminating subscriber called by the originating subscriber. A home location register (HLR) stores subscriber information such as terminal information and additional service information. Herein, the HLR stores information about the terminating subscriber.
When the originating subscriber calls the terminating subscriber (e.g., the NSN number), the originating MSC sends a location request invoke message LOCREQ to the HLR of the terminating subscriber in order to acquire location information of the terminating subscriber. The location request invoke message LOCREQ includes dialed digits DGTSDIAL and a system ID parameter (not shown) for the originating MSC. Here, the originating subscriber refers to an originating subscriber who uses a normal PSTN phone or a mobile phone. The terminating subscriber refers to a mobile subscriber registered in the homezone service.
The HLR determines MDN termination by analyzing the received dialed digits DGTSDIAL and sends a routing information request invoke message ROUTREQ to the terminating MSC in order to acquire routing information. The routing information request invoke message ROUTREQ includes a mobile identification number (MIN).
Upon receipt of the routing information request invoke message ROUTREQ, the terminating MSC assigns a temporary local directory number (TLDN) for routing. In addition, the terminating MSC sends a routing information request result message routreq (RoutingRequest RETURN RESULT) to the HLR of the terminating subscriber. The routing information request result message routreq includes a routing information parameter TLDN.
Upon receipt of the routing information request result message routreq, the HLR of the terminating subscriber sends a location request result message locreq (LocationRequest RETURN RESULT) to the originating MSC. The originating MSC detects the TLDN number included in the location request result message locreq, routes the detected TLDN number to the terminating MSC, and performs a call setup process.
The terminating MSC sends a redirecting request invoke message redreq (RedirectingRequest) to the originating MSC for call forwarding, in such a termination-inactivated state as a busy state, a no-answer state and a no-page response state. At the moment, the terminating MSC includes a redirecting reason parameter REDREASON (RedirectingReason) in the redirecting request invoke message.
Upon receipt of the redirecting request invoke message redreq from the terminating MSC, the originating MSC sends a transfer number (or a call forwarding number) request invoke message TRANUMREQ (TransferToNumberRequest) to the HLR of the terminating subscriber in order to find out a call forwarding number (or a transfer number to which an incoming call is to be forwarded). The transfer number request invoke message TRANUMBREQ includes a redirecting reason parameter REDREASON.
The HLR of the terminating subscriber searches a call forwarding number of the terminating subscriber, inserts the searched call forwarding number in the transfer number (or a call forwarding number) request result message tranumreq (TransferToNumberRequest RETURN RESULT) and then transmits the transfer number request result message tranumreq to the originating MSC. The originating MSC then detects the call forwarding number from the transfer number request result message tranumreq and performs the termination process again. The redirection request (“REDREQ”) is sent from the terminating MSC to the originating MSC.
However, in such a call forwarding service, the terminating MSC determines whether to transfer (or forward) an incoming call in the termination-inactivated state, based on a calling feature indicator parameter (CallingFeatureslndicator) provided from the HLR to a VLR (Visitor Location Register). The calling feature indicator parameter CallingFeatureslndicator, however, defines only a call forwarding feature field for the MDN number. Therefore, it is not possible to use the calling feature indicator parameter CallingFeatureslndicator as call forwarding information for other numbers except the MDN number.